Chapter Nine Homework Review

The words weather and climate

-refer to different size scales -refer to different time scales Explanation: Weather is small scale and short-term, while climate describes the average state of an atmosphere.

The total mass of Venus 's atmosphere is 4.84×1020 kg and nitrogen makes up about 1.8 percent of its atmospheric mass. What is the mass of nitrogen in Venus's atmosphere?

8.71 x 10&18kg Explanation: The fraction of the mass of Venus 's atmosphere contributed by nitrogen is: 1.8100×4.84×1020=8.71×1018

A bar is a measure of atmospheric pressure, where one bar is equivalent to Earth's atmospheric pressure at sea level. Venus's atmosphere has a pressure of 92 bars. Water pressure in Earth's oceans increases by one bar for every 10 m of depth. How deep would you have to go to experience pressure equal to the atmospheric surface pressure on Venus?

920m deep Explanation: Since one bar is equivalent to 10 meters of depth in water, you need to multiply the number of bars of Venus's atmosphere by 10 meters per bar. The atmospheric pressure is 92 bars. 92 bars × 10 m/bar = 920 meters

Based on the relation shown here between rising carbon dioxide (CO2) concentrations and average global temperatures, what is a logical prediction about what would happen if CO2 levels were to continue to rise?

Average global temperatures would increase. Explanation: Average global temperatures have clearly been rising overall right along with rising carbon dioxide (and methane) concentrations. Notice that it is very important to use the full range of information shown in the graph, and not just any one small section of it. A common current argument is that average temperatures have leveled off, which would seem to be true if you only used the last 10 to 15 years. But the overall trend is very clearly that as CO2 levels increase the average temperature increases as well, and there is no reason to think that this should not continue to be the case.

Label different features of the greenhouse effect on Earth.

Explanation: From left to right in the image: the Sun delivers radiation that heats the ground; infrared radiation is radiated from the ground; some infrared radiation is reradiated back to the ground by greenhouse gases; and infrared radiation escapes into space in order to balance the incoming radiation from the Sun.

Place in chronological order the following steps in the formation and evolution of Earth's atmosphere:

Explanation: Hydrogen and helium were captured from the protoplanetary disk during the formation of Earth. Hydrogen and helium are lost from the weak gravitational force of Earth. Then, volcanoes, comets, and asteroids increased the amount of volatile materials. Small organisms released CO2, which in turn promoted plant growth that turned the CO2 back into oxygen. The oxygen enabled the growth of new life-forms.

Rank, from greatest (at top) to smallest (at bottom), the seasonal variations of the terrestrial planets.

Greatest to Smallest: Mars, Earth, Venus, and Mercury Explanation: Due to its greater orbital eccentricity and thinner atmosphere, Mars has the greatest seasonal variations. Earth has less seasonal variation than Mars because of its smaller eccentricity and thicker atmosphere. The equator of Venus is almost lined up with its orbit, so the planet has essentially no tilt as well as a more circular orbit than the other planets, so it has very little seasonal variation. Mercury has no atmosphere at all, so no seasons.

The following graph shows the concentrations of carbon dioxide (CO2) and methane (CH4) in Earth's atmosphere for the past few hundred thousand years along with global temperatures. How do the current levels of carbon dioxide and methane in the atmosphere compare with the values seen over the last 800,000 years?

The current concentrations of both are far higher than the rest of the graph. Explanation: The current concentrations of both methane and carbon dioxide are far above the normal variation in levels seen over the past 800,000 years. Methane especially has more than doubled in a short amount of time. This graph also shows a clear correlation between high concentrations and high temperatures, which is why there is much concern about these higher than average concentrations!

The following graph shows the relative concentrations of carbon dioxide (CO2) and methane (CH4) in Earth's atmosphere for the past few hundred thousand years. What, if any, correlation is there between the concentrations of carbon dioxide and methane?

Their concentrations appear to rise and fall together. Explanation: Concentrations of carbon dioxide and methane have tended to rise and fall together due to recurring cycles in Earth's orbit and tilt.

Venus is hot and Mars is cold primarily because

Venus has a much thicker atmosphere. Explanation: Venus's exceptionally thick atmosphere translates into a very strong greenhouse effect. An analogy is that Mars has a comforter with two down features in it, while Venus is covered with several down comforters of heavy-winter thickness.

The oxygen molecules in Earth's atmosphere

are the result of life Explanation: Earth, Mars, and Venus most likely started out with similar atmospheres and experienced similar geological histories, but the development of life on Earth increased the amount of oxygen in Earth's atmosphere.

The following graph shows the concentrations of carbon dioxide (CO2) and methane (CH4) in Earth's atmosphere for the past few hundred thousand years along with global temperatures. What is the correlation between concentrations of these two chemicals and global temperature?

When concentrations are high global temperatures are high. Explanation: High concentrations of carbon dioxide and methane tend to go right along with higher global temperatures, and similarly with low concentrations and lower temperatures. Can you see why there is reason for concern about the increasingly higher concentrations of these two chemicals?

The following graph shows the relative concentrations of carbon dioxide (CO2) and methane (CH4) in Earth's atmosphere for the past few hundred thousand years. Approximately how often is there an especially high peak in concentrations of both chemicals?

every 100,000 years Explanation: Concentrations of carbon dioxide and methane have tended to peak together at especially high concentrations approximately every 100,000 years due to recurring cycles in Earth's orbit and tilt. Notice how these peaks also correspond to especially high global temperatures.

Auroras are the result of

the interaction of particles from the Sun and Earth's atmosphere and magnetic field. Explanation: Auroras occur when charged particles from the Sun, trapped in our planet's magnetic fields, rain down on our atmosphere.

The AstroTour illustrates what the surface temperatures of Venus, Earth, and Mars would be without atmospheres, and it also shows the current value for each planet, with their actual atmospheres. Place the planets in order based on the discrepancy between their surface temperatures with and without their atmospheres.

Least to Most difference: Mars, Earth, and Venus Explanation: Earth's atmosphere is transparent to visible light, so photons pass right through without interference from the molecules of the atmosphere. However, since the atmosphere is opaque to the infrared light emitted from Earth's surface, the infrared photons are absorbed and re-emitted many times before reaching the upper boundary of the atmosphere. The presence of an atmosphere around a planet gives it a higher surface temperature than it would otherwise have. Equilibrium is achieved when energy input balances output. The temperatures of the three planets are these: Venus Earth Mars Without atmosphere 250 K 210 K 170 K With atmosphere 737 K 288 K 210 K Whether you compare them by absolute or percent difference, the order of increasing difference between the two conditions is Mars, Earth, and Venus.

The distinct layers of Earth's atmosphere vary in temperature in a somewhat surprising way. Arrange these four layers in ascending order, based on the temperature at the upper boundary of each.

Low to high in temp: Mesosphere, Troposphere, Stratosphere, and Thermosphere. Explanation: As shown on a figure in your text, the approximate temperatures at the upper boundaries of the various layers are as follows: Mesophere: 210 K Troposphere: 230 K Stratosphere: 275 K Thermosphere: 570 K

Whether a planet has an atmosphere or not depends on a number of factors: mass, temperature, composition of the crust, volcanic activity, and complex evolutionary processes. Rank the planets according to how well they retain their atmospheres, using the following criteria: • The planet that still maintains its primary atmosphere, ranks first. • The planet that lost its primary atmosphere but retains a dense secondary atmosphere, ranks second. • The planet that lost its primary atmosphere and retains a tenuous secondary atmosphere, ranks third. • The planet that retained neither its primary nor secondary atmospheres, ranks last.

Most successful to Least Successful: Jupiter, Venus, Mars, and Mercury Explanation: Small mass made all the terrestrial planets lose their primary atmospheres. Tiny, hot Mercury was not able to retain its secondary atmosphere, either. While both planets retained their secondary atmospheres, Venus, with eight times the mass, did so much more effectively than Mars. And giant Jupiter, 5 AUs away from the warmth of the Sun, never lost its primary atmosphere.